Cylinder breech for small firearms

ABSTRACT

A breech mechanism wherein a bolt actuated locking sleeve is telescopingly mounted on a breech bolt and is operable to cam breech bolt locking lugs outwardly into abutting cooperation with forwardly facing, breech chamber recess wall means.

United States Patent 1 Bielfielelt 1 Jan. 2, 1973 [54] CYLHNDER BREECH FOR SMALL [56] References Cited FHREARMS UNITED STATES PATENTS [75] Inventor: Heinz Bielfeldt, 233 Eckernforde,

2,601,808 7/1952 Clarke ..89/19O Germany 2,948,195 8/1960 Lmder [73] Assignee: J. P. Sauer & Sohn GmbH, Eckern- 2,078,155 4/1937 Pelo ..89/176 forde, Germany Primary Examiner-Benjamin A, Borchelt [22] Flled March 1971 Assistant Examiner-C. T. Jordan [21] Appl. No.: 126,462 Attorney-Burns, Doane, Swecker & Mathis [30] Foreign Application Priority Data [57] ABSTRACT A breech mechanism wherein a bolt actuated locking Nov. 19, 1970 Germany ..P 20 56 929.3 sleeve is telescopingly mounted on a breech bolt and is operable to cam breech bolt locking lugs outwardly [52] U5. Cl ..42/16, 89/190 into abutting cooperation with forwardly facing, [51] Int. Cl ..F41c 11/06, F41d 1/00 breech chamber recess wall means [58] Field of Search ..42/16; 89/176, 190

7 Claims, 2 Drawing Figures CYLENDER BREECH FOR SMALL FIREARMS GENERAL BACKGROUND, OBJECTS AND SUMMARY OF lNVENTION The invention relates to a cylinder breech for small arms.

Customarily, breech studs are attached at the front end of the rotatable breech bolts (or block) of the chamber, in the case of such cylinder breeches. These studs slide in longitudinal grooves during the longitudinal shifting of the bolt in the chamber and, for the purpose of locking, engage in their front end. position with annular grooves on the inside surface of the chamber casing.

in the case of this manner of locking, it is disadvantageous that the surfaces absorbing the detonation recoil are very small in the case of a certain predetermined constructional volume, so that they no longer have a sufficient stability for the high gas pressures of modern shells. Furthermore, the tooling of annular grooves in the walls of the casings must be made very precisely, so that all studs will carry loads evenly. The adjustment of the dimensioning of the breech components, which is made with a tolerance of 0.1 mm, is accomplished by machining. If the required tolerance has not been maintained and the distance is too long, then a very expensive subsequent working is required. The longitudinal breech chamber grooves moreover take up a part of the peripheral breech chamber surface, so that as a result, the guidance of the chamber will be influenced disadvantageously.

It has also been known to attach, in the peripheral direction, interrupted parts of a thread on the front end of the bolt, instead of breech studs, which can also be disposed in larger numbers and in several rows one behind the other, and to provide corresponding counterthreads in the breech chamber casing. Thus, longitudinal breech chamber grooves are available in the inside wall of the chamber casing for the purpose of longitudinal breech bolt shifting, in which grooves the sections of the breech bolt thread can slide. Thusly, it is true, the load carrying surfaces are enlarged. However, the remaining disadvantages of the combination of a breech with breech studs remain.

Therefore it will be the purpose of the invention to produce a cylinder breech for small arms where the load carrying surfaces will be considerably enlarged, which cylinder will permit an easy adjustment of the tolerance of the breech. [n this cylinder, grooves running in the axial direction in the inside wall of the chamber casing or cylinder can be omitted. As a result of this, the guidance of the breech bolt will be considerably improved and the individual parts of the assembly can be manufactured as simply as possible.

According to the invention this problem will be solved, in the case of a cylinder breech for small firearms, through the fact that a locking body with which the bolt handle is connected has been limited, longitudinally shiftably, in the casing bore in relation to the body of the chamber. Further, spreading elements, distributed over the locking body periphery have been inserted between the forward front surface of the locking body and the opposite surface of the body of the breech chamber, pointing backward and supported by this locking body. The rear ends of these elements can be spread radially toward the outside. A groove for reception of the rear, spreading-apart ends of the spreading elements is located in the cylinder wall of the casing, with a supporting surface pointing forward for engagement with said elements. A conical ramp surface to permit expansion of the spreader elements has been provided on the front surface of the locking casing.

The central tube therefore is free of longitudinal grooves and thus is a very good guidance device. The machining, especially tooling the longitudinal grooves, is reduced. With the use of spreader elements, far greater recoil forces can be absorbed than with conventional breech studs.

It will be advantageous to allow the locking body to slide on a piece of the neck of the chamber bolt which is smaller in diameter than the remainder of the chamber, whereby connection of these two elements is established, with axial play permitted by way of a latch mechanism. At the same time, the projection of the latch will engage with a longitudinal slit of the bolt of the chamber. Upon opening the breech, first of all the locking body is drawn axially back a little, which draw back will be sufficient to slide the spreader elements inward away from the conical ramp surface at the front end of the locking element. Upon a further rearward movement, the spreader elements will be located inside the bore of the chamber casing and thus the bolt can be shifted longitudinally rearwardly whenever the latch projection engages the rear edge of the longitudinal slit.

It will be advantageous if the spreader elements are spring loaded toward the inside, i.e., chamber axis, so that they will be sure to move out of the annular groove in the chamber casing when the breech is opened. in a favorable instance, these elements consist of individual sections of a revolving bolt which are disposed, evenly distributed over the periphery.

It will be effective to provide, in the breech chamber, as a supporting surface for the spreader elements, a supporting surface adapted to or conforming to the slope of the spread-out spreader elements. This supporting surface may be disposed on the breech bolt adjoining the conical ramp surface. This supporting surface will hold and support the spreader elements in their spread-apart position while the cylinder breech is locked.

An intermediate ring disposed axially between a breech bolt shoulder and the spreader elements, may be provided for the purpose of an easy and exact adaptation of manufacturing tolerances. This ring has a bearing surface for the front ends of the spreader elements. The axial distance between the spreader elements and the bolt shoulder is determined by customary spacers.

DRAWINGS The invention will be explained once more on the basis of an embodiment shown in the drawing, by way of example, so that thereby its characteristics and advantages will clearly become apparent.

FIG. 1 shows a perpendicular longitudinal cut through a cylinder breech according to the invention in closed position; and

FIG. 2 shows a corresponding perpendicular cut, in which however, the locking body, just prior to or after its locking position, stands with the bolt handle swiveled by about DETAILED DESCRIPTION In the figures, the breech casing has been designated by 11, the body, block, or bolt of the chamber by 12 and the bolt handle by 13. V

The bolt 12 of the chamber is revolvable by operating the bolt connected handle 13 and it is also longitudinally slidable. The customary inside breech bore, with a constant diameter goes through the breech casmg.

The rear end of breech bolt element 12 has been developed as a long neck element 14 with a small diameter. On neck 14, first of all, sits an intermediate ring 15 adjoining the reduced section of the diameter, or bolt shoulder. This intermediate ring 15 serves as a support bearing for-spreader elements l7,with these elements 17 being distributed evenly over the periphery. This bearing 15 is axially adjustable by way of spacer means l6.'The spreader elements have rounded forward facing edges by means of which they lie in a circular annular groove 15a of the intermediate ring 15. They can be rotated in the annular groove in a limited way, in relation to the longitudinal axis of the breech.

Spreader elements may comprise longitudinal segments of a cylindrical body and have rear, bolt locking ends comprising segments of a frustoconical surface, conformingly engageable with recess surface b (subsequently discussed).

The bolt neck element 14 has a further recess 14a, in the pivoting area of the spreader elements. Recess 14a provides a support 18 for a coil spring 19. This spring 19 engages a hook-like projection 17a of each spreader element 17. Spring 19 is a compression spring which presses against projections 17a of the spreader elements 17 and biases them toward the breech axis with an inward swinging force. The inward movement of the spreader elements is limited by the spring supports themselves.

Thus, as shown in FIG. 1, hook-like portions 17a of spreader elements 17 function as pivot inducing levers, in relation tothe spreader element seat means defined by groove 15a. That is to say, the engagement of the left end of the coil spring means 19, shown in FIG. 2, with the lever-like hook portion 17a will exert a biasing influence on the spreader elements 17, tending to cause the rearward or breech casing engaging ends of these elements to pivot toward the longitudinal breech and bolt axis, i.e., the axis of bolt reciprocation.

As is equally apparent, spring 19 will continuously bias spreader elements 17 into pivotally engaged and seated engagement with insert ring seat means 15a.

In the area of the spreader elements 17, and especially their ends, an annular groove 20 has been recessed in the cylinder wall of the breech casing. Groove 20 has a front frustoconical element 20a which is in the shape of an acute angled cone. This surface 20a and groove 20 permits the spreading apart of the spreader elements 17 inside the casing bore. A rear frustoconical element 20b which has a considerably more obtuse angled surface, serves as a supporting, axially engageable surface for the end surface of spreader elements 17 whenever the latter are spread apart.

A locking element 21 is mounted inside the casing bore, and is guided slidably on neck element 14 of the body of the chamber. Bolt handle 13 is inserted in and mounted on locking element 21.

Locking body 21 has a ramp surface 21a in the shape of an obtuse angled, frustoconical configuration, disposed contiguous with the ends of the spreader elements. Surface 21a is succeeded by or adjacent a supporting surface 21b in the shape of an acute angled cone, the functions of which will be explained later on.

The front end of the locking body 21, however, extends coaxially over the rear end of the spring support 18 located in recess 14a. This insures that the support 18, possibly consisting of individual segments, cannot move radially out of this recess.

As will be noted, surfaces 21b and 20a are generally parallel. Thus, when surface 21b is conformingly supporting undersurface portions of lugs 17 in the breech bolt securing position of FIG. 1, the lugs 17 are held in the breech bolt locking position without bolt 12 and surface 20a wedging forces on the lugs 17.

A'latch 23 has been inserted in the locking bolt body 21, in the rear end of this locking bolt body. Latch23 extends in the longitudinal direction of the breech bore and is pivotal around an axle 22 disposed transversely to it and carried by body 21. Latch 23 has a tang portion 23a which engages, i.e., enters, a longitudinal slit 14b in the bolt neck portion 14. The arrangement of projection 23a of the latch, in relation to the longitudinal slit 14b, has'been made in such a way that upon pulling the locking body 21 back on the neck piece 14, the projection 23a will encounter the rear edge of the slit 14b only when the ramp surface 21a has moved past the rear ends of spreader'elements 17, thereby permitting the latter to swing toward the inside. Latch 23 and longitudinal slit 14b cannot be seen in FIG. 2 since in this figure the locking body 21, and thus also the bolt body 12 of the chamber, have been rotated by means of bolt handle 13. This joint rotation results from tang 23a slidably engaging the sides of slit 14b.

In FIG. 1, the completely closed and bolted position of the breech is shown. It will be advisable, however, to explain the locking process, first of all beginning with the position shown in FIG. 2, in which the breech has of course already been shut but not bolted. This bolting is accomplished by pivoting the bolt handle downward by about 90, whereby the bolt handle is guided in a peripheral guide or side slot of the chamber casing. This guide means causes locking sleeve or body 21 to slide forward in response to its pivoting movement of the neck element 14 of the body 12 of the chamber, with bolt body 12 already being seated at the front or barrel end. Then the spreader elements 17 will be cammed outward on ramp surface 21a and enter annular groove 20. When this has been accomplished, continued pivoting of bolt handle 13 will cause the locking body 21 to slide axially by a certain distance underneath the spreader elements, and support them with supporting surface 21b which has the shapeof an acute angled cone. This position is shown in FIG. 1.

The force exerted on the body of the chamber during recoil is then transmitted via the almost axially aligned spreader elements to breech casing 11, via the relatively large supporting end surfaces of the spreader elements.

When opening the breech, the movements take place in a reverse sequence, and compression spring 19 will cause the spreader elements 17 to swing inwardly as soon as the support by the locking body 21 is withdrawn.

In the case of a further opening of the breech, beyond the position shown in FIG. 2, the projection 23a of the latch will then engage at the rear end of slit Mb, so that bolt body 12 of the chamber, together with locking body 21, are pulled backwards, the used cartridge ejected, and another shell from the magazine moves from the magazine to a feed position in front of the barrel.

From the foregoing discussion, it will be appreciated that breech chamber 1 1 will be provided with a bolt rotary movement-permitting slot or recess means, somewhat similar to the recess means 78 described in U.S. Weatherby Pat. No. 3,013,355 (1961).

In order to provide the initial increment of unlocking, rearward movement of the locking sleeve 21 (when the bolt 13 is moved upwardly from the closed chamber and locked position of FIG. 1 to the unlocked position of FIG. 2 this bolt guiding recess means in the breech body may have a cam-like configuration, curving upwardly from right side portion of the chamber (viewing the chamber from the rear, i.e., left to right as shown in FIG. 1) in a generally counterclockwise direction and extending somewhat rearwardly, i.e., away from the barrel. Thus, this recess means may comprise a generally helical segment configuration, operable to cammingly induce the longitudinal displacement of the sleeve means 21 (as shown by FIG. 2 in relation to FIG. 1) in response to a 90 counterclockwise movement of bolt 13 about the axis of chamber 11.

As will also be understood, FIGS. 1 and 2 illustrate conventional breech and bolt components including cartridge case extractor means, firing pin means, etc. In order not to obscure the present invention, these components have not been described in detail. However, their structure and mode of operation is now well understood in the art. For example, extractor means and the firing pin arrangements shown in FIGS. 1 and 2 correspond generally to those shown in the aforesaid U.S. Weatherby Pat. No. 3,013,355.

SUMMARY OF ADVANTAGES AND SCOPE OF INVENTION A particular advantage of the invention resides in the provision of a breech bolt locking lug arrangement wherein operative maneuvering of the locking lug is reliably controlled by manual maneuvering of a breech bolt handle. In the absence of manual maneuvering, the breech bolt locking elements remain in a bolt locking condition, when the breech is closed.

The arrangement for securing the locking lugs effectively avoids a wedging type phenomena which might tend to impede the releasing of the locking lugs from a locked position.

The overall arrangement is characterized by a unique degree of compactness and operational reliability.

In describing the invention, reference has been made to a preferred embodiment. However, those familiar with the firearms art and this disclosure may recognize deletions, substitutions and other modifications or changes not specifically described but which would fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

I. A cylinder breech for small firearms comprising:

casing means;

bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable locking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged by said end portions of said spreader elements, and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; and said bolt means includes relatively restricted neck means slidably supporting said locking body means; and said breech further includes latching means interconnecting said locking body means and said neck means and operable to permit limited telescoping movement of said locking body means relative to said neck means. 2. A cylinder breech as described in claim 1 wherein: said latching means comprises latching tang means carried by said locking body means, and slit means on said neck means extending longitudinally of said neck means and slidably receiving said tang means. 3. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable locking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged by said end portions of said spreader elements, and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and cammingsurface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; and resilient biasing means carried by said bolt means, biasingly engaging said spreader elements, and yieldably urging said end portions of said spreader elements toward a longitudinal axis of said bolt means. 4. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable looking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged-by said end portions of said spreader elements and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; and intermediate ring means carried by said bolt means and disposed generally axially between said spreader elements and said cartridge engaging end of said bolt means; said intermediate ring means providing bearing surface means pivotally supporting and securing ends of said spreader elements. 5. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable locking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged by said end portions of said spreader elements, and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; and said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; said bolt means including relatively restricted neck means slidably supporting said locking body means; latch means interconnecting said locking body means and said neck means and operable to permit limited telescoping movement of said locking body means relative to said neck means; said latch means including latching tang means carried by said locking body means, and slit means on said neck means extending longitudinally of said neck means and slidably receiving said tang means; resilient biasing means carried by said bolt means, biasingly engaging said spreader elements, and yieldably urging said end portions of said spreader elements toward a longitudinal axis of said bolt means; said spreader elements comprising generally cylindrical segments, said segments further being generally uniformly,

circumferentially distributed about the reciprocation axis of said bolt means; said supporting surface means comprising a generally frustoconical configuration, the periphery of which is inclined relative to the reciprocation axis of said bolt means by a generally acute angle, said supporting surface means being operable to conformingly engage undersurface portions of said spreader elements, which undersurface portions generally face said axis of bolt means reciprocation; said camming surface means comprising a generally frustoconical configuration generally facing said cartridge engaging end of said bolt means; and intermediate ring means carried by said bolt means and disposed generally axially between said spreader elements and said cartridge engaging end of said bolt means; said intermediate ring means providing bearing surface means pivotally supporting and securing ends of said spreader elements. 6. A manually operable breech locking mechanism comprising:

breech chamber means;

breech bolt means slidably mounted in said breech chamber means for reciprocation along an axis;

manually operable sleeve means journaled on said bolt means and operable to move axially of said means and opening generally toward said reciprocation axis of said bolt means, said recess means including:

a generally frustoconical forward portion operable bolt means in response to rotary movement of said to ece S d outwardly positioned locking lug sleeve means within said chamber means; means, and breech bolt locking lug means mounted on said bolt 3 generally frustoconical. rearward, locking g means and operable, in an outward position, to g g Portion opel'able to engage ends of Said lock said bolt means with said chamber means; outwardly Positioned l king lug means and resilient means yieldably urging said locking lug y D rearward axial movement of means toward said reciprocation axis of said bolt means; camming means carried by said sleeve means and said bolt means relative to said breech chamber means. 7. A mechanism as described in claim 6 wherein said camming means of said sleeve means comprise a frustoconical surface aligned generally parallel with said forward, frustoconical portion of said locking recess means.

operable, in response to movement of said sleeve means toward said locking lug means, to cam said locking' lug means outwardly away from said reciprocation axis of said bolt means; and locking recess means carried by said breech chamber 

1. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable locking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged by said end portions of said spreader elements, and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; and said bolt means includes relatively restricted neck means slidably supporting said locking body means; and said breech further includes latching means interconnecting said locking body means and said neck means and operable to permit limited telescoping movement of said locking body means relative to said neck means.
 2. A cylinder breech as described in claim 1 wherein: said latching means comprises latching tang means carried by said locking body means, and slit means on said neck means extending longitudinally of said neck means and slidably receiving said tang means.
 3. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable locking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable tO be engaged by said end portions of said spreader elements, and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; and resilient biasing means carried by said bolt means, biasingly engaging said spreader elements, and yieldably urging said end portions of said spreader elements toward a longitudinal axis of said bolt means.
 4. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable looking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged by said end portions of said spreader elements and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; and intermediate ring means carried by said bolt means and disposed generally axially between said spreader elements and said cartridge engaging end of said bolt means; said intermediate ring means providing bearing surface means pivotally supporting and securing ends of said spreader elements.
 5. A cylinder breech for small firearms comprising: casing means; bolt means slidably mounted in said casing means, reciprocable therein along an axis, and having a cartridge engaging end; manually operable locking body means mounted on said bolt means for longitudinal movement relative thereto; a plurality of spreader elements connected with said bolt means, said spreader elements having end portions facing away from a cartridge engaging end of said bolt means and operable to move generally outwardly of said bolt means; bolt locking recess means carried by said casing means and facing generally inwardly thereof; said bolt locking recess means having a rearward portion operable to be engaged by said end portions of said spreader elements, and a forward portion, intermediate said rearward portion and said cartridge engaging end of said bolt means, and operable to permit said outward movement of said end portions of said spreader elements; and said locking body means including supporting surface means operable to maintain said spreader elements in an outward position, lockingly engaging said rearward portion of said recess means, and camming surface means, operable in response to longitudinal movement of said locking body means relative to said bolt means, to move said spreader elements to said outward position; said bolt means including relatively restricted neck means slIdably supporting said locking body means; latch means interconnecting said locking body means and said neck means and operable to permit limited telescoping movement of said locking body means relative to said neck means; said latch means including latching tang means carried by said locking body means, and slit means on said neck means extending longitudinally of said neck means and slidably receiving said tang means; resilient biasing means carried by said bolt means, biasingly engaging said spreader elements, and yieldably urging said end portions of said spreader elements toward a longitudinal axis of said bolt means; said spreader elements comprising generally cylindrical segments, said segments further being generally uniformly, circumferentially distributed about the reciprocation axis of said bolt means; said supporting surface means comprising a generally frustoconical configuration, the periphery of which is inclined relative to the reciprocation axis of said bolt means by a generally acute angle, said supporting surface means being operable to conformingly engage undersurface portions of said spreader elements, which undersurface portions generally face said axis of bolt means reciprocation; said camming surface means comprising a generally frustoconical configuration generally facing said cartridge engaging end of said bolt means; and intermediate ring means carried by said bolt means and disposed generally axially between said spreader elements and said cartridge engaging end of said bolt means; said intermediate ring means providing bearing surface means pivotally supporting and securing ends of said spreader elements.
 6. A manually operable breech locking mechanism comprising: breech chamber means; breech bolt means slidably mounted in said breech chamber means for reciprocation along an axis; manually operable sleeve means journaled on said bolt means and operable to move axially of said bolt means in response to rotary movement of said sleeve means within said chamber means; breech bolt locking lug means mounted on said bolt means and operable, in an outward position, to lock said bolt means with said chamber means; resilient means yieldably urging said locking lug means toward said reciprocation axis of said bolt means; camming means carried by said sleeve means and operable, in response to movement of said sleeve means toward said locking lug means, to cam said locking lug means outwardly away from said reciprocation axis of said bolt means; and locking recess means carried by said breech chamber means and opening generally toward said reciprocation axis of said bolt means, said recess means including: a generally frustoconical forward portion operable to receive said outwardly positioned locking lug means, and a generally frustoconical, rearward, locking lug engaging portion operable to engage ends of said outwardly positioned locking lug means and thereby prevent rearward axial movement of said bolt means relative to said breech chamber means.
 7. A mechanism as described in claim 6 wherein said camming means of said sleeve means comprise a frustoconical surface aligned generally parallel with said forward, frustoconical portion of said locking recess means. 